This invention relates in general to certain new and useful improvements in mattresses having fluid-containing internal chambers and the method of making the same and, more particularly, to mattresses of the type stated which include a central liquid chamber which is surrounded by an upper material-containing chamber but which permits the liquid chamber to be substantially continuous with the lower surface of the mattress and with the material-containing chamber extending around the periphery of the liquid chamber.
In recent years, water beds have become widely commercially acceptable and have found substantially increased use. It has now been fairly well recognized that water beds, that is those forms of beds which employ a water filled mattress, have not only enjoyment value, but therapeutic value as well. In general, it has been found that many people find that it is not only more enjoyable, but is more restful to sleep on a water bed mattress than other forms of conventional mattresses filled with solid, but nevertheless, resilient, material.
The present commercially available water bed mattresses generally comprise a rectangular shell formed primarily of some form of a fairly flexible plastic material and which is filled with water. This form of water bed mattress is thereupon supported in, and by virtue of its construction is required to be supported in, a rigid frame.
In recent years, there have been various other forms of water bed mattresses which include an air frame peripherally surrounding a water bladder, as for example in the Penn et al. U.S. Pat. No. 3,778,852, and the Pennington et al. U.S. Pat. No. 3,787,907. This latter form of water bed mattress, which includes a surrounding air frame, is typically referred to as an air frame water bed mattress. These air frame mattresses differ substantially from the purewater bed mattress, without the air frame, in that those mattresses including the air frame do not require the employment of a rigid structural frame.
The presently available water bed mattresses which do not include the air frame suffer from a large number of deficiencies such as the fact that these mattresses do not obviate the problem of wave action created in the water in the water chamber due to a sudden localized force. Consequently, when a person lies upon a water bed mattress without the surrounding air frame, the water shifts substantially, thereby creating substantial wave action and also the attendant displacement of the surface contour of the mattress.
The other forms of water bed mattresses including the air frame surrounding the water bladder, as exemplified by the Penn et al. Patent and the Pennington et al. Patent mentioned above, also suffer from a number of substantial disadvantages. It has again been well established that those water beds which include the surrounding air frame and which avoid the necessity of a rigid frame do not provide the required degree of comfort. It has been theorized that these water bed mattresses eliminate some of the wave action which is created by a sudden localized force. Nevertheless, it is also well established that the air bladder is relatively incompressible with respect to the water bladder. Consequently, the water bed mattresses which include the surrounding air frame do not provide constant and adequate support. The same generally holds true of those water bed mattresses which do not employ the air frame surrounding the water bladder. One of the primary problems of each of these conventional water beds is that they do not provide equal water flotation with respect to the entire upper surface of the water bed mattress.
Another important disadvantage with respect to the water bed mattresses of each of the aforementioned types is that they are not constantly sized with respect to a supporting structure or, otherwise, a supporting frame. Consequently, difficulty often arises in fitting the water bed mattress, when filled with water, or otherwise with water in the water bladder and air in the air bladder, to the supporting frame or a supporting structure. Even more importantly, these water bed mattresses which are presently commercially available do not provide any adequate safety feature in the event of punctures in the mattress itself which could result in immediate and substantial discharge of water with resultant damage.
The present invention obviates these and other problems in the provision of a fluid-containing mattress which includes a pair of upper and lower sheets having peripherally extending, perpendicularly struck side wall flaps. These side wall flaps are secured to each other in order to form an outer peripheral end wall, thereby defining a rectangularly shaped water bed mattress. A panel extends across portions of the upper sheet and is sealed to the upper sheet by one heat seal in close proximity to the end wall and is also sealed to the upper sheet by another heat seal spaced inwardly from the first heat seal in order to thereby provide a material-containing chamber along the upper periphery of the mattress. In a more preferred aspect of the invention, the panel is a continuous panel extending peripherally around the upper sheet of the mattress and is heat sealed to the upper sheet somewhat inwardly of its peripheral margin to form the second of the heat seals. Moreover, the other end of the panel which is heat sealed to the upper sheet is preferably heat sealed to this sheet at a point in close proximity to the end wall.
In accordance with this construction, the upper material-containing chamber constitutes and upper flotation chamber which provides peripheral edge support on the mattress. In addition, this upper material-containing pocket prevents a so-called "bottoming-out" when one sits on the edge of the mattress. This form of mattress also equalizes for differential weight and body mass.